Removed access of freed memory in GrContext dtor
Removed access of freed memory in GrContext dtor

http://codereview.appspot.com/6488111/



git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@5479 2bbb7eff-a529-9590-31e7-b0007b416f81

mrobinson/skia,mrobinson/skia,metajack/skia,metajack/skia,Cue/skia,metajack/skia,mrobinson/skia,metajack/skia,mrobinson/skia,Cue/skia,Cue/skia,Cue/skia,mrobinson/skia